Is this a radiant barrier?

[FACTOR]

Is that a radiant barrier in the photo? Sorry it's not too clear or obvious, but I was wondering if it's just plastic waterproofing, reflecting, or if it's a foil radiant barrier. What does it look like to you?

Thanks.

[Crossy]

Looks like a radiant barrier to me

[IMHO]

Yes, that is a radiant barrier (foil) but it's been installed incorrectly - the foil should go under the battens, not above them. It will still work, but not as effective as it could have been.

[FACTOR]

Yes, that is a radiant barrier (foil) but it's been installed incorrectly - the foil should go under the battens, not above them. It will still work, but not as effective as it could have been.

Ok. Thanks. Should it go under the battens to allow for a thin space for proper airflow? If so, wouldn't the curved shape of the roofing tiles allow for such a space and for airflow?

Thank you.

[FACTOR]

Yes, that is a radiant barrier (foil) but it's been installed incorrectly - the foil should go under the battens, not above them. It will still work, but not as effective as it could have been.

Ok. Thanks. Should it go under the battens to allow for a thin space for proper airflow? If so, wouldn't the curved shape of the roofing tiles allow for such a space and for airflow?

Thank you.

I meant to ask: if the barrier should have indeed gone under the battens, not above them, now that they are above them, won't the curved shape of the tiles allow for the space for airflow?

Thanks.

[rsokolowski]

Concur, it is radiant barrier.

[IMHO]

Yes, that is a radiant barrier (foil) but it's been installed incorrectly - the foil should go under the battens, not above them. It will still work, but not as effective as it could have been.

Ok. Thanks. Should it go under the battens to allow for a thin space for proper airflow? If so, wouldn't the curved shape of the roofing tiles allow for such a space and for airflow?

Thank you.

I meant to ask: if the barrier should have indeed gone under the battens, not above them, now that they are above them, won't the curved shape of the tiles allow for the space for airflow?

Thanks.

The reason for placing them under the battens is to provide an air gap. Any areas of physical contact will conduct heat into the roof cavity, negating some of it's effectiveness. The fact that the tiles have a small contact patch because of their profile is the reason why it will still work even though it's been installed wrong

Note: it's not about airflow - it's about using air as an insulator.

Edited December 13, 2013 by IMHO

[FACTOR]

Thanks for the above replies.

Next question: now I am thinking of installing R27 fibreglass insulation (Microfibre) on the attic floor (i.e. the upper side of the ceiling). Do you think that, combined with the radiant barrier, will provide for an efficiently insulated attic/roof so that I can have good inside temperatures and noise reduction? (I realise the answer to my question might be obvious, but I'd appreciate your insights and opinions.)

I realise I should also insulate the walls, right? Is a radiant barrier also used on walls, or just for roofs and attics?

Thank you.

[Beardog]

Thanks for the above replies.

Next question: now I am thinking of installing R27 fibreglass insulation (Microfibre) on the attic floor (i.e. the upper side of the ceiling). Do you think that, combined with the radiant barrier, will provide for an efficiently insulated attic/roof so that I can have good inside temperatures and noise reduction? (I realise the answer to my question might be obvious, but I'd appreciate your insights and opinions.)

I realise I should also insulate the walls, right? Is a radiant barrier also used on walls, or just for roofs and attics?

Thank you.

You need to think about getting rid of the heat opposed to trapping it R 27 would be great in Europe , England ,US & towards Melbourne Australia. The wrap you have now should be way adequate if you have adequate ventilation to remove the excess heat in the attic area.If you live in Chiang Mai or Chiang Rai maybe then & I don't think I would put anything as near as aggressive as R 27. Where I live near Pattaya you want to keep the house as cool as you can in the daytime . The benefit there is you don't need to run the ac all the time & it keeps the cost down for utilities as well.We only get 2 weeks cold here & usually less cold than it this year so heat would not be what you want at all!

[bbradsby]

Your radiant barrier at the roof is to reject radiant heat off the concrete tiles, and does require an air gap. So wherever your tiles rest on the barrier (at each batten) you will have conduction of the tiles' heat into your roof steel framing. But, what you have is better than nothing at all.

The R-27 ceiling insulation is required minimum in my opinion, but rare in LoS. In the US, R-30 is spec'd for hot summer climates where the temp far exceeds those in LoS, while winter temps still reach freezing. But even in LoS, the attic temperatures can be such that heat noticeably radiates down through the ceiling quite easily without proper insulation. BTW, Where are you buying your insulation, and is it one batt or built-up over several layers of batts? I've not seen anything past 100mm [4"] in HomePro, etc.

For those who don't install a radiant barrier just under the roof, get your insulation batts with foil facing to reject radiant heat at the ceiling level; the foil should face the attic, not the ceiling since its there to reject the heat. Otherwise, install radiant barrier over the normal plastic-wrapped batts at the ceiling.

For your walls, the most important thing is to keep 10:00am-5:00pm sun off your window/door glass with exterior shading/overhangs/landscaping. Next is to use 20cm AAC block, painted with light colored radiant barrier paint on the outside. Then, make sure you have proper door & window seals/weatherstripping, else all will be for naught in even a slightly breezy day.

With these measures your air conditioning bill will be minimized / thermal comfort maximized with or without aircon.

Edited December 24, 2013 by bbradsby

[IMHO]

Have any of those suggesting batts ever used them in Thailand? If so, have you been up into your roof space lately to see what's living there now?

[Thai at Heart]

The amount of radiant heat stored in tiles is enormous. You can get rid of all the trapped air you like but the radiant heat will heat up the ceiling very quickly.

PU foam is the most effective I've come across so far.